The Transgenic Core will provide two essential services for all Program investigators: 1) routine DNA sequencing and 2) preparation of transgenic and genetically-defined mice. These two services will provided by two separate units which will operate independently of each other. Each unit will integrate into and expand existing facilities providing similar service. The Sequencing Facility will support all projects in this Program and meet their routine sequencing needs. The facility currently operates 2 Applied Biosystems Automatic DNA Sequencers. The Transgenic Facility will produce transgenic mice by both direct injection of DNA into fertilized mouse embryos (the classical method) and by the introduction of embryonic stem (ES) cells in which genes have been manipulated into mouse blastocysts. Because several key genes involved in the biological processes under investigation in this Program encode proteins essential in early development, this Core will provide Program investigators with the ability to conditionally knock-out specific genes in specific cell types and at specific stages of cell activation by generating several strains of mice expressing cre and/or flp recombinases under control of skin-specific promoters. Furthermore, the Core will have the expertise to generate chimeric and mosaic animals thereby allowing studies on gene function and regulation during differentiation. Both of these powerful genetic approaches permit the study of protein function in vivo of molecules that in somatic deficient mice would be lethal. Thus, this Core will provide essential and modern technology for Program investigators.